blood component therapy

Component therapy The therapeutic use of specific portions–components of blood–eg, factor VIII concentrates, packed red cells, or platelets rather than whole blood

blood component therapy

Transfusion of one or more of the components of whole blood. The blood components may have been taken from the patient previously (autologous transfusion) or donated by someone else (homologous transfusion). Except in the case of acute hemorrhage, the transfusion of whole blood is rarely needed. Use of a component rather than whole blood permits several patients to benefit from a single blood donation. Blood components used in clinical medicine include packed red blood cells (RBCs); leukocyte-poor RBCs; frozen glycerolized RBCs; thawed deglycerolized RBCs; washed RBCs; whole blood; heparinized whole blood; granulocytes; platelets; and plasma and plasma fractions. The latter include antihemophilic factor (Factor VIII), prothrombin complex (Factors VII, IX, and X), gamma globulin, and albumin.

Patient care

Irradiation of blood by gamma rays (gamma irradiation) incapacitates donor lymphocytes in whole blood, RBCs, platelets, or granulocytes. These lymphocytes are blocked from proliferating in response to foreign antigens, esp. those in the bone marrow, of immunocompromised recipients, causing transfusion-associated graft-versus-host disease. In patients who are not immunocompromised, the donor white blood cells (WBCs) are destroyed. Irradiated blood is given to patients who are donating or receiving bone marrow transplants or who have hematological or lymphatic cancers. In addition, blood used for intrauterine or neonatal exchange transfusions and blood donated by a biological relative also is irradiated.

Washing blood (RBCs, platelets) in 0.9% sodium chloride removes most, but not all, of the antibodies that could trigger an adverse reaction, esp. in patients with a history of hypersensitivity reactions to blood transfusions, even when given antihistamine prophylaxis. Washed RBCs must be given within 24 hours because the risk of bacterial contamination is increased when the saline is injected into the bag of RBCs.

Use of leukocyte-poor blood reduces the risk of unwanted responses to WBCs (leukocytes), antibodies, and cytokines by the recipient. WBCs can be eliminated by using special filters in the intravenous line or through aphoresis. The process is used for patients with a history of allergic reactions to blood products or those expected to require multiple transfusions. It also prevents transmission of cytomegalovirus (CMV) to immunocompromised patients.

Screening blood for CMV and RBC antigens helps to identify CMV-negative blood, which is needed for high-risk patients. More than half of persons over 35 years of age have been infected with CMV. However, this screened blood is beneficial for premature infants; infants under age 4 weeks; recipients of intrauterine transfusion regardless of the mother’s CMV status; any patient who requires a bone marrow or organ donor transplant if the marrow or organ donor also is CMV-negative; and CMV-negative patients who are potential transplant candidates, pregnant, about to undergo splenectomy, or have AIDS/HIV or congenital immune deficiency.table; blood transfusion;

Component

When it is used

Approximate volume (in mL) infused or typical preparation

Storage/viability

Expected outcome

Packed red blood cells

When needed to restore the oxygen-carrying capacity of the blood of the patient

470

Refrigerated or frozen; may last as long as 42 days

An increase in hemoglobin of 1 g/dL

Platelets

In severely thrombocytopenic patients, e.g., < 40,000/dL in hemorrhaging patients, or < 10,000, in patients who are not yet bleeding

Despite having multiple guidelines on indications of blood component therapy in individual derangements, there is no clear-cut evidence regarding benefit from such transfusions and in practice, transfusions also depend on the availability of blood and blood components.

Most indications for whole blood transfusion are now well-managed exclusively with blood component therapy, yet the use of fresh whole blood was still seen in the public hospital on a routine basis, when there was no compelling evidence for the use of whole blood in preference to component therapy for its routine.

Blood component therapy has many advantages like more efficient utilization of each unit of blood by taking the advantage of differential storage properties of various elements, reduces exposure of patients to unnecessary cellular elements and plasma proteins, minimizes bacterial contamination and eliminates risk of various non-immunogenic reactions like circulatory overload (Turnwald and Pichler, 1985).

I like to refer them to an article published by The Task Force on Blood Component Therapy of the American Society of Anesthesiologists: Anesthesiology, which says: "The principal conclusions of the task force are that red blood cell transfusions should not be dictated by a single hemoglobin "trigger" but, instead, should be based on the patient's risks of developing complications of inadequate oxygenation.

We have significant worldwide experience in the development and commercialization of blood processing systems, blood component therapy, hospital based transfusion medicine and the regional blood center system," concluded Clibourn.

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